Different kinds of long-term variability from Cygnus X-1

We present a study of the long-term variability of Cyg X-1 using data from the RXTE/ASM and the RXTE/PCA during the time between the two soft states of 1996 and 2001/2002. This period has been characterized by many short ASM flaring episodes which we have identified as "failed state transitions". The 150 d period which has been seen before and shortly after the 1996 soft state is not obviously present in the ASM rate during most of this time. Applying selection criteria from our pointed RXTE/PCA observations to exclude the flaring episodes we show that the 150 d period can indeed still be significantly detected in the hard state. Furthermore, while the ~420 d timescale associated with the flaring is reduced in the selected hard state count rate, it is still pronounced in the temporal evolution of the corresponding hardness ratios. The Ryle radio flux is also consistent with the 150 d period being present but distorted during this time.Comment: 4 pages, 6 figures, to appear in Proceedings of "X-ray Timing 2003: Rossi and Beyond", ed. P. Kaaret, F.K. Lamb, & J.H. Swan

Spontaneous symmetry breaking as a resource for noncritically squeezed light

In the last years we have proposed the use of the mechanism of spontaneous symmetry breaking with the purpose of generating perfect quadrature squeezing. Here we review previous work dealing with spatial (translational and rotational) symmetries, both on optical parametric oscillators and four-wave mixing cavities, as well as present new results. We then extend the phenomenon to the polarization state of the signal field, hence introducing spontaneous polarization symmetry breaking. Finally we propose a Jaynes-Cummings model in which the phenomenon can be investigated at the single-photon-pair level in a non-dissipative case, with the purpose of understanding it from a most fundamental point of view.Comment: Review for the proceedings of SPIE Photonics Europe. 11 pages, 5 figures

Cicatrización del fibrocartílago meniscal de la Rodilla : estudio Experimental

Para estudiar la cicatrización de las lesiones meniscales se ha realizado un estudio experimental en conejos. Se han practicado tres tipos de lesiones en el menisco, transversal, longitudinal parameniscal y longitudinal interna alejeda del paramenisco. Posteriormente el defecto creado era reparado mediante puntos sueltos con material reabsorvible. Se ha estudiado el fenómeno de cicatrización desde el punto de vista histológico desde la semana a los tres meses. Los resultados muestran que la cicatrización es fundamentalmente extrínseca a partir de la capacidad plástica de la membrana sinovial. Las heridas longitudinales parameniscales cicatrizaron sin dificultad, las transversales casi en toda su anchura y las longitudinales en zona avascular cicatrizaron principalmente en su porción anterior gracias a la invasión de sinovial hiperplásica desde la inserción tibial del ligamento cruzado anterior.To study the healing of meniscal tears, the authors hav e carried out an experimental work in rabbits. They performed three types of tears in the internal menisci, radial, peripheral longitudinal (in the parameniscal zone) and longitudinal within of the parameniscus. The menisci were reparated by suture with absorbible material. The healing phenomenon has been histologically studied from the first wee k to three months after. The results showed that the cicatrization is mainly extrinsic by the plastic capacity of sinovial membrane. The longitudinal tears in the parameniscus heal without difficulty, the transversal tears almost in their whol e width and the longitudinal tears at the avascular zone healed principally in the anterior portion by the invasion of hyperplasic sinovial from the tibial insertion of the anterior cruciate ligament

Fibrocartílago meniscal como biomaterial de sustitución en los Defectos Osteocondrales. Estudio experimental en el conejo con injertos homólogos

Los autores presentan un estudio experimental en el cual han empleado homoinjertos de fibrocartílago meniscal, para reparar defectos osteocondrales localizados en zona de carga, del cóndilo medial de la rodilla del conejo. Han sido estudiados 33 animales, realizando un estudio histológico, con periodos de evolución comprendidos entre una semana y 22 meses. Los homoinjertos meniscales parecen ser capaces de restaurar una superficie articular funcional. Conservan su estructura y celularidad a lo largo de toda la experiencia consiguiendo un perfecto anclaje al lecho óseo, adaptándose a la carga y sin producir cambios en el cartílago articular vecino. No se han producido rechazos.The authors report on an experimental study, employing meniscal fibrocartilage homo grafts to repair osteochondral defects in the weightbearing area of medial condile of rabbit knee. Thirty-three animals were studied by histological means for periods of one week to 22 months. The meniscal fibrocartilage homograft appeared capable of restoring a functional articular surface, maintaining its entire histological structure and celularity throughout the experiment, obtaining a perfect union with the bone tissue, adapting to the weightbearing and not modifying the neighboring articular surface. No evidence of rejection was observed